(728c) Controlling the Assembly of Semiconducting Nanoparticles With Conjugated Polymers for Solar Cell Applications

Hybrid organic-inorganic solar cells have emerged as a newly-developed branch in the third generation of solar cell technology. It is well-known that the morphology inside the active layer of the solar cell is the crucial factor to the performance. In this study, we propose a fabrication procedure to control the morphology of the active layer, building up the solar cell with a “bottom-up” method. We focus on controlling the arrangement of the inorganic nanocrystal, CdSe tetrapods (TPs), when the conjugated polymer, poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), serves as the templating agent at the air/water interface by utilizing the Langmuir-Blodgett (LB) technique. All the experiments are monitored by Brewster angle microscopy (BAM). The thin film of CdSe TPs/MEH-PPV are transferred by Langmuir-Blodgett or Langmuir-Schaefer (LS) technique and characterized by the atomic force microscopy (AFM) and the transmission electronic microscopy (TEM). The preliminary results show that solar cells made via the LB method has three times higher power conversion efficiency (PCE) than the one made from the conventional spin-coating methods. The higher PCE from the LB method benefits from the percolating network of packed CdSe TPs, which provides a pathway for electrons to travel through the active layer to the cathode. This study highlights the importance in controlling the structure of the inorganic material within an organic matrix for solar cells.